The NCAA has announced Wednesday that it has replaced the Rating Percentage Index (RPI) as their primary tool for evaluating teams for the NCAA tournament. The new system will be the NCAA Evaluation Tool (or NET), and its intended to be used this coming season. Senior Vice President of Basketball for the NCAA had this to say about the change:
“What has been developed is a contemporary method of looking at teams analytically, using results-based and predictive metrics that will assist the Men’s Basketball Committee as it reviews games throughout the season. While no perfect rankings exist, using the results of past tournaments [as test sets] will help ensure that the rankings are built on an objective source of truth.”
Is this a big deal? Kind of. RPI had been used to help select and seed teams in the men’s NCAA basketball tournament since the early 1980s. The women’s tournament adopted the same method a year later. The concern is that the RPI had too much influence in the seeding process. Then the rules were altered slightly, and the committee decided that quality of win was more important. This meant if you won an away game, your quality of win was greater than if you won a home game. In general, the RPI is a ranking system based on a teams wins and losses, as well as its strength of schedule.
How does it work? The index looks at a team’s winning percentage (25%), its opponents’ winning percentage (50%) and the winning percentage of those opponents’ opponents (25%). Confusing, right? Well, I’m going to confuse you even further: The opponents’ winning percentage and the winning percentage of those opponents’ opponents both comprise the strength of schedule (SOS). Thus, the SOS accounts for 75% of the RPI calculation and is 2/3 its opponents’ winning percentage and 1/3 its opponents’ opponents’ winning percentages.
The new system (NET) relies on “games results, strength of schedule, game location, scoring margin, net offensive and defensive efficiency and the quality of wins and losses”. The dates of games and the order in which they are played are not included in an effort to give equal importance to early- and late-season games. Also, the margin of victory is capped at 10 points, preventing teams from getting a boost by running up the score against inferior opponents.
What we don’t know is how these new elements of the ranking will be determined or who will be calculating new statistical categories in the system – such as net offensive and defensive efficiency. RPI wasn’t perfect but it was transparent. This definitely seems to be looking at more aspects of the team and looking at it holistically. The NCAA’s news release did say the new NET model used team performance data to predict the outcome of games in test sets and optimized that until it was as accurate as possible Will this help teams to be seeded better? Well, that’s the aim. We will certainly be writing about this again in the new year, as we’re heading into the March Madness tournament.